Function stripFences

packages/lang-core/src/parser/parser.ts:267–358

(input: string)

/** Extract code from markdown fences, or return as-is if no fences found.
 *  String-context-aware: skips ``` inside double-quoted strings. */
export function stripFences(input: string): string {
  const blocks: string[] = [];
  let i = 0;

  while (i < input.length) {
    // Scan for opening ``` while tracking string context
    let fenceStart = -1;
    while (i < input.length) {
      const nextI = skipString(input, i);
      if (nextI > i) {
        i = nextI;
        continue;
      }

      const c = input[i];
      if (
        c === "`" &&
        i + 1 < input.length &&
        input[i + 1] === "`" &&
        i + 2 < input.length &&
        input[i + 2] === "`"
      ) {
        fenceStart = i;
        break;
      }
      i++;
    }

    if (fenceStart === -1) break;

    // Skip language tag until newline
    let j = fenceStart + 3;
    while (j < input.length && input[j] !== "\n") j++;
    if (j >= input.length) {
      // No newline after opening fence (streaming) — take everything after fence marker + lang tag
      blocks.push(input.slice(fenceStart + 3).replace(/^[^\n]*\n?/, ""));
      i = input.length;
      break;
    }
    j++; // skip the newline

    // Scan for closing ``` while tracking string context
    let closePos = -1;
    let k = j;
    while (k < input.length) {
      const nextK = skipString(input, k);
      if (nextK > k) {
        k = nextK;
        continue;
      }
      const c = input[k];
      if (
        c === "`" &&
        k + 1 < input.length &&
        input[k + 1] === "`" &&
        k + 2 < input.length &&
        input[k + 2] === "`"
      ) {